I just recently got into pc gaming. Unfortunately I don't have the money to get a new laptop or any system. Fortunately I already had a Dell Studio XPS 1340, which from what I heard isn't bad for gaming. Is there anything i can do for the laptop to have it run games smoother? (I've been playing Batman Arkham Asylum (kind of laggy), street fighter IV (works fine), and I'm getting Assassin's Creed).

Here's what I have

Dell Studio XPS 1340
Intel(R) Core(TM)2 Duo CPU P8700@2.53GHz
RAM: 4GB
64-bit Operating System
NVIDIA GeForce 9500M (GF 9400MG + GF 9200MGS)

Looks like you are pretty well maxed out with the laptop. It's not that bad. Gaming laptops cost big bucks, $1200 or higher. How big is your hard drive?

I second Tmagic; also, remember that, due to the way laptops are manufactured, it's usually impossible to upgrade a laptop beyond replacing the hard drive, memory, optical drive (if it's removable), or the wireless card (if that's removable).